When British authorities raided the London offices of StubHub this past summer, they seized records of the ticket website's most successful sellers, including a Canadian whose scalping empire is exposed in the Paradise Papers.

Officials from the U.K.'s Competition and Markets Authority (CMA) confiscated computer records to search for evidence of suspected illegal activity by scalpers who sell mass quantities of tickets using StubHub, sources confirmed.

British authorities are cracking down on how so-called secondary market websites obtain and resell tickets. Parliament passed a law this year that will target scalpers in the U.K. who use aggressive software to beat out regular fans in the race to get tickets.

Canadian Julien Lavallée, who is among those StubHub classifies as its "top sellers," is caught up in two separate investigations in the U.K., one by the CMA and the other by law enforcement officials at the National Trading Standards (NTS) agency.

The Paradise Papers leak of offshore financial records, released this week by the International Consortium of Investigative Journalists, includes documents that reveal Lavallée is a multinational scalper based in Quebec who has moved millions of dollars worth of tickets in Canada, the U.S. and U.K.

Business records found in the leak show he uses StubHub, Vivid Seats and Ticketmaster as "main channels" to scalp his tickets.

"Lavallée, on the first day, stuck out like a sore thumb," said a source familiar with the NTS probe into mass purchases of online concert tickets.

"What he is doing is sending something — a bot, a robot — into the system," the source said. "He just bought a hundred tickets, and he probably bought them in less than an hour. And that is not possible. It's not physically possible."

Lavallée refused to answer questions about his online ticket purchases or his relationship with StubHub. But in a statement, he said his Quebec operation "considers all its activities are in accordance with laws and regulations in jurisdictions in which it operates and sells its products."

StubHub served with warrant

Reg Walker, a U.K. event security specialist hired by major concert venues and promoters, said the raid was part of a broader investigation into four main ticket resale sites in Britain: Get Me In, Seatwave, Viagogo and StubHub.

"I was made aware [CMA] sent out information requests to all four platforms and said, 'Look, we want to know who's selling all these tickets through your sites. Can you provide this list?'"

According to Walker, Stubhub refused the request, so the CMA got a warrant.

StubHub spokesperson Roisin Miller declined to answer questions about the raid when contacted by the Guardian newspaper.

"We understand the CMA investigation is ongoing and therefore await the outcome of this," Miller wrote in an email.

U.K. exposes scalper secrecy

What ultimately put Lavallée on investigators' radar is a transparency law in the U.K. that requires sites like StubHub to post information about resellers operating as businesses.

No such law exists in Canada.

Lavallée used a company called I Want Ticket Inc, registered on the British Isle of Man, to post on StubHub in the U.K. He dissolved the company in October, one day after a reporter with the International Consortium of Investigative Journalists tried to find its offices on the island, which is a well-known tax haven.

He created a stir last year after journalists and fan advocates spotted him posting hundreds of concert tickets on StubHub for U2, Take That and The Weeknd.

Adam Webb of the London-based Fan Fair Alliance, a group that campaigns against the online scalping industry, says Lavallée is moving so many tickets it makes a mockery of StubHub's marketing as a site for average fans to sell their tickets if they fall ill, break a leg or just can't make it to a show.

"What's happening here is not fan-to-fan activity. It's [scalper]-to-fan activity," he said. "All of the platforms operate on that basis ... They are active and complicit in this process."

StubHub declined CBC's requests for an interview and wouldn't comment on its relationship with Julien Lavallée.

"StubHub holds all sellers to a very high standard and requires they follow all relevant laws," the company said in an emailed statement.

"StubHub agrees that the use of bots to procure tickets is unfair and anti-consumer. StubHub has always supported anti-bots legislation and encourages policy-makers to look comprehensively at the host of factors that impact a fan's ability to fairly access, buy, resell, or even give away tickets."